You have too make sure you have all the air out the system.Maybe Empty system check for plugged lines ,check thermostat by putting it in hot and seeing what temperture it opens i believe it is around 172 Degrees F.Check rad cap, water pump etc.I had an airlock in my 01 and it would start to heat up fairly fast.Start with getting any air out the system. Best regards.

It seems every other new member comes in here with almost exact same questions :)

Now, steps for diagnostics:

Open the radiator (when cold, preferably) and look in there. You said the heater is cold - so it's quite likely that you're way low on coolant. If so, refill it. Make sure you do that in several steps - pour coolant (open the small tap on top of the radiator to let the air out easier) while "massaging" the upper radiator hose ("burping" the air out). Close everything, run the engine (heater on full) until it warms up (on the first step, you could runs in just for a few minutes), stop, let it cool (optional - to avoid burning yourself) - you will see the air in the radiator again. Add coolant, and repeat the above steps until no more air is evident in the radiator (if you did not achieve that in about 2-3 tries - stop, you probably have other problems). Al that time - WATCH THE TEMPERATURE, do not let it accidentally go above normal.

Look for leaks, watch for smoke, smell for coolant (sweet). Find the leak - if there is one. Also look and smell for coolant in the exhaust.

Look at the coolant overflow reservoir. Is ti full? Does it overflow? Are there bubbles coming into the overflow tank from the radiator (when you rev high or when you just stopped after a drive)? Can you smell exhaust/fuel in the coolant tank? Do you see oily film or sludge in there? These are the symptoms of the blown headgasket (cylinder to coolant blowby) - the most common and severe issue of DOHC Foresters engines.

Check the oil. Does it look clear and smell normal? No murky/whitish stuff in there?

Check the thermostat and waterpump operation (idle to normal operating temperatures, see when/if thermostat opens by checking the temperature of the lower radiator hose, or by looking into the open radiator - if you feel comfortable doing it that way). If the engine has warmed up, but the radiator/hoses are cold - replace the thermostat.

Thanks for the info guys/gals, I added fluid tonight and it looks like I am way low on coolant, there were air bubbles coming out for a good 10 minutes while the motor was running, I'll bleed the rest of the air out and add some more fluid tomorrow.

At that point I'll see how things go, if the problem persists I'll check for leaks and follow the posted troubleshooting tips.

... symptoms of the blown headgasket (cylinder to coolant blowby) - the most common and severe issue of DOHC Foresters engines....

Were you thinking he had DOHC? I thought only the turbo models were DOHC, and he merely said he had a 1997 Forester. Were they all DOHC back then?
Did the NA models (like my 2008 LLBean) with their SOHC also have head gasket problems, or is it confined to the DOHC models?

Were you thinking he had DOHC? I thought only the turbo models were DOHC, and he merely said he had a 1997 Forester. Were they all DOHC back then?
Did the NA models (like my 2008 LLBean) with their SOHC also have head gasket problems, or is it confined to the DOHC models?

AFAIK all pre-mid-98 production are DOHC - at least in US (although US did not get MY97, the engine should be the same). Pre-03 SOHC tend to leak externally (more pronounced on 99-00); newer models do not exhibit HG problems. Assuming Subaru did not step on the same rake again with the latest models, you should not worry about it.

1. I don't see any oil in the coolant,
2. any other way to see whether its the headgasket?

1 is consistent with the phase-1 HG trouble

2. Cylinder compression test might reveal the leak, but most likely will not. But you can pretty much eliminate all other possibilities.

Since the coolant is being forced out, something must be replacing it. It might be exhaust (headgasket), coolant/water vapor (might happen if part of the system is clogged or thermostat does not open), or residual air expansion.

So, here is a question: are you sure you properly refilled the radiator (see my first post above about the multi-stage procedure)? Does your heater work now? If "no" is the answer to any of the above - do it again, properly. Fill to top, idle to normal temperature (do not let it overheat; heater ON), stop, cool, refill, repeat. Done it three times and still have air int he radiator? It's the head gasket.

Now, let's start at the point where you have full coolant system with no air This is critical! Every other test assumes that this has been done properly.

Start the car (assuming - cold), let it idle. Look at what is happening to the overflow tank. Does it start to overflow before the engine even warms up fully? And try this - with the engine warmed up (IDLE, DO NOT DRIVE!), rev the engine for a second or two. If bubbles come up almost immediately - it's the headgasket.

Here is another question - how does it overheat? Does it: A. loose coolant and then overheats, or B. starts to overheat immediately (heats continually from cold to hot, without much pause on "normal"), while no or little coolant has been lost yet? If B, you have circulation problems (waterpump, clogging), if A - it's the headgasket.

Btw, make sure you check the radiator cap. Just buy a replacement (a few bucks in any autoparts store) to see if that solves the problem. Unlikely, but it's cheap.

Another test for head gasket - the sniff test of the air in the coolant overflow. You could do it using your noise, but it's somewhat toxic and not very reliable. The proper way is to test for CO2 and/or hydrocarbons - this can be done with a proper kit ($60-100?, not easy to find), or at most auto shops for about $40-60. Positive test means headgasket. But I'd say that the tests above should be sufficient, since you have an engine prone to exactly this kind of failure, and if all the symptoms match.... Well, at least once fixed properly, this problem should not be coming back.

Thanks. My own DIY repair jouney started with no mechanical expertise whatsoever, so I know how difficult if can be to locate or even understand a problem without at least some prior hands-on experience with that particular type of problem. But help or at least a proper walkthrough of the procedure from somehow who has that experience can help a lot - both in resolving a problem as well as overcoming the psychological barrier that most people have when it comes to working on their own car instead of entrusting is to a "professional"... who does not give a damn about the well-being of your vehicle.